索引器【C#】

索引：

索引，索的是实例化的编号，派生的子类，第   [ N ]   个儿子。

用数组的方式访问实例。 

返回的是实例的，一个属性值。

声明：        this [ 索引 ]

    public string this[int index]
      {
         get
         {
           
         }
         set
         {
          
         }
      }


 public int this[string name]   //根据名字，确定实例编号
  {
         get
         {
            int index = 0;
            while(index < size)
            {
               if (namelist[index] == name)
               {
                return index;
               }
               index++;
            }
            return index;
         }

  }

using System;
namespace IndexerApplication
{
   class IndexedNames
   {
      private string[] namelist = new string[size];
      static public int size = 10;
      public IndexedNames()
      {
         for (int i = 0; i < size; i++)
         namelist[i] = "N. A.";
      }
      public string this[int index]
      {
         get
         {
            string tmp;

            if( index >= 0 && index <= size-1 )
            {
               tmp = namelist[index];
            }
            else
            {
               tmp = "";
            }

            return ( tmp );
         }
         set
         {
            if( index >= 0 && index <= size-1 )
            {
               namelist[index] = value;
            }
         }
      }

      static void Main(string[] args)
      {
         IndexedNames names = new IndexedNames();
         names[0] = "Zara";
         names[1] = "Riz";
         names[2] = "Nuha";
         names[3] = "Asif";
         names[4] = "Davinder";
         names[5] = "Sunil";
         names[6] = "Rubic";
         for ( int i = 0; i < IndexedNames.size; i++ )
         {
            Console.WriteLine(names[i]);
         }
         Console.ReadKey();
      }
   }
}

2重载索引器（Indexer）

using System;
namespace IndexerApplication
{
   class IndexedNames
   {
      private string[] namelist = new string[size];
      static public int size = 10;
      public IndexedNames()
      {
         for (int i = 0; i < size; i++)
         {
          namelist[i] = "N. A.";
         }
      }
      public string this[int index]
      {
         get
         {
            string tmp;

            if( index >= 0 && index <= size-1 )
            {
               tmp = namelist[index];
            }
            else
            {
               tmp = "";
            }

            return ( tmp );
         }
         set
         {
            if( index >= 0 && index <= size-1 )
            {
               namelist[index] = value;
            }
         }
      }
      public int this[string name]
      {
         get
         {
            int index = 0;
            while(index < size)
            {
               if (namelist[index] == name)
               {
                return index;
               }
               index++;
            }
            return index;
         }

      }

      static void Main(string[] args)
      {
         IndexedNames names = new IndexedNames();
         names[0] = "Zara";
         names[1] = "Riz";
         names[2] = "Nuha";
         names[3] = "Asif";
         names[4] = "Davinder";
         names[5] = "Sunil";
         names[6] = "Rubic";
         // 使用带有 int 参数的第一个索引器
         for (int i = 0; i < IndexedNames.size; i++)
         {
            Console.WriteLine(names[i]);
         }
         // 使用带有 string 参数的第二个索引器
         Console.WriteLine(names["Nuha"]);
         Console.ReadKey();
      }
   }
}

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